Application of a Copper Shim

[SaturnX]

Hey Everyone,
Well I'll be assembling my TBird 900 system soon and I have a quick question. I'm using a copper shim on the cpu, though do I have to apply thermal paste to it? (I'm using Artic Silver II) So would I first place some on the core, and then spread a thin layer onto both sides of the shim? or one side? Thanks for any input.

--Mark

 

[MadRat]

The idea is to carry heat to the heatsink, not from the ceramic. It would probably be more effective if the copper shim was insulated from the ceramic if anything. Perhaps a piece of trace paper would work, but then again you'd most certainly be throwing off its intended design tolerances.

 

[compuwiz1]

Tell ya a little story. There was a guy I sold a Tbird to....don't remember the exact specs, but let's say it was supposed to run at 1.3GHz, like it was tested. BTW, I don't use a shim to test with and have installed well over 350 heatsinks on Tbirds and durons and have never cracked a core.
He wants to be careful, and I don't blame him. He installs a shim, sets up his system and then writes me to tell me that it will only do 1250, not 1300 like I promised. We talked about the shim and we agreed he would very carefully install his heatsink without it. Guess what.... the other 50MHz suddenly came back.

I believe there is a trade off, but have not installed one personally, but think they retain heat around the core, instead of letting it dissipate thru the HSF.

Just food for thought........

 

[Tominator]

compuwiz1
I've often though that airflow was much more important that the mass of a heatsink. I see no need for memory heatsinks for instance. The mass of the heatsink would negate any gain in cooling and could only insulate. The only exception I could come up with would be the need for massive heat transfer. We only come close to this with CPU cooling as the CPU is by far the hottest part in anyones system.

 

[AMB]

I remember seeing that you were better off WITHOUT using one. I shall have a look though the archives...

 

[Blain]

If the shim is too thick, it will keep your CPU from contacting the HS. If it's too thin, what good is it doing, if it doesn't make contact?
It must match your slug thickness VERY VERY closely!

Better get those micrometers out!

 

[ginfest]

I gotta agree with you Blain, i tried a shim at one time, my PC booted but suddenly all hell broke loose. I checked the temp in the BIOS, 70C and rising! Evidentially the shim was too thick, although it looked OK to the naked eye b/4 assemble. In lieu of making your own shim to exact tolerance for your particular chip, I say don't use a shim. It may do more harm than good.
Mike G

 

[Blain]

I knew I remembered reading about Copper Shims somewhere.

 

[MadRat]

I've tried copper sheeting to attach multiple heatsinks and that does work. I think the biggest problem is that copper readily reabsorbs heat too well to use it without having it impregnated into the bottom of the heatsink. Any gap, even microscopic, allows air to insulate the transfer of heat from shim to heatsink.

I'm just guessing, but I am starting to think insulation shims would have been better than copper shims.